Coarse sagging of the skin and facial musculature occurs gradually over time due to gravity and chronic changes in connective tissue associated with aging. Invasive surgical treatment to tighten such tissues is common, for example by face-lifts. In these treatments for connective tissue sagging, a portion of the tissue is usually removed, and sutures or other fasteners are used to suspend the sagging tissue structures. On the breasts, the muscular fascia and ligaments form a layer superficial to the muscles and beneath the skin and subcutaneous fat. Breast sagging is due to a process in which the suspensory (Cooper's) ligaments become lax. Surgical tightening of the underlying muscular fascia and ligaments is needed for surgical correction through a procedure referred to as mastopexy, or more commonly known as breast lifts.
Radio frequency (RF) devices have been used to produce heating and shrinkage of skin on the face and breast, with some success as a non-invasive alternative to surgical lifting procedures. However, RF is a dispersive form of energy deposition. It is impossible to control precisely the heated tissue volume and depth, because resistive heating of tissues by RF energy occurs along the entire path of electrical conduction through tissues. Another restriction of RF energy for non-invasive tightening of Cooper's ligaments is unwanted destruction of the overlying fat and skin layers. High impedance to RF within fat, overlying the suspensory connective structures intended for shrinking, leads to higher temperatures in the fat than in the target suspensory structures. Similarly, mid-infrared lasers and other light sources have been used as attempts to non-invasively heat and shrink connective tissues of the dermis. However, light is not capable of non-invasive treatment of Cooper's ligaments, because light does not penetrate deeply enough to produce local heating there. Below a depth of approximately 1 mm, light energy is multiply scattered and cannot be focused to achieve precise local heating.